Los Altos Hills, California
California Water Service — Los Altos Suburban 2025 Consumer Confidence Report. Hardness (total) 305 ppm (137–440) and 97 ppm (96–98) on the labeled columns. The row is not labeled CaCO3. Same official booklet as Los Altos. Total chlorine 1.5 ppm (ND–3.0), MRDL 4, 2025. No Measure S-style ban turned up — check the sewer agency on the bill.
- Total chlorine1.5 ppm (ND–3.0)
Best match for Los Altos Hills
Whole-house carbon for chlorine
Check the sanitation district before installing a salt system.
That is chlorine. A whole-house carbon filter with an NSF/ANSI 42 chlorine claim is the usual match. A softener will not take chlorine out.
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Other options that still fit
Confirm hardness on the current CCR before buying
Open the current CCR for grains. This file does not invent a number from a ranking site. A salt softener needs a drain if it is legal at the address.
Shop salt-based softenersShop salt-free conditionersShop water test kits
Under-sink reverse osmosis
The under-sink RO we actually run is Cloud RO — NSF/ANSI 58, kitchen tap, not a whole-house tank. Check the exact listing if PFAS is why you are shopping. Shop Amazon first for under-sink RO, or buy Cloud direct. Waterdrop is a tankless option if you want that path. A certifier-listed pitcher is the cheap first step. Nobody is paying for a medical claim.
Shop under-sink reverse osmosisBuy Cloud RO directShop Waterdrop reverse osmosisShop PFAS-listed pitchers
Test the tap first
A homeowner kit is a start. It is not a state-certified lab. Use a certified lab when the decision is expensive.
On the report
- Water utility
- California Water Service — Los Altos Suburban
- Hardness
- Hardness (total) 305 ppm (137–440) and 97 ppm (96–98) on the labeled columns. The row is not labeled CaCO3. Same official booklet as Los Altos. — California Water Service Los Altos Suburban 2025 Water Quality Report
- Disinfectant
- Total chlorine 1.5 ppm (ND–3.0), MRDL 4, 2025. — California Water Service Los Altos Suburban 2025 Water Quality Report
- Brine / salt to the sewer
- Check the sanitation district before installing. No city or sanitation-district residential self-regenerating softener ban like LACSD Measure S or IEUA Ordinance § 2.6 turned up on the pages we opened. That is not a statewide ban finding. Ask the agency on the sewer bill before you cut a brine drain.
Also around here
Extra context besides the utility report and the chart above — geology, an unregulated table, or a published study. Not a second set of printed tap numbers.
- MicroplasticsWHO’s 2019 review examined studies that found microplastic particles in treated tap and bottled water in many places. That is a published-occurrence finding, not a number from this city’s water-quality report, and we do not invent a particles-per-liter count for the tap.Microplastics in drinking-water — World Health Organization
- PFASEPA’s Fifth Unregulated Contaminant Monitoring Rule required community systems this size to test 29 PFAS and lithium in 2023–2025. Open the UCMR 5 Data Finder for this PWS. This file does not invent a detection.Fifth Unregulated Contaminant Monitoring Rule — U.S. Environmental Protection Agency
Los Altos Hills drinking water on this file is California Water Service — Los Altos Suburban, PWS CA4310001. No city or sanitation-district residential self-regenerating softener ban like LACSD Measure S or IEUA Ordinance § 2.6 turned up on the pages we opened. That is not a statewide ban finding. Ask the agency on the sewer bill before you cut a brine drain. This is not a legal opinion.
The 2025 report prints Hardness (total) 305 ppm (137–440) and 97 ppm (96–98) on the labeled columns. The row is not labeled CaCO3. Same official booklet as Los Altos. Total chlorine 1.5 ppm (ND–3.0), MRDL 4, 2025. Kitchen shopping stays the Cloud RO / Waterdrop path already used on other cities if a listing is why you are looking.
Sources
- 2025 Consumer Confidence Report (PWS CA4310001) — California Water Service — Los Altos Suburban / State Water Resources Control Board. Accessed 2026-09-11.
Updated September 11, 2026. A city file is chemistry we can cite plus the sewer rule. No invented detections.